Discussion about the Korg PolySix synthesizer

I own a vintage (70s) Korg MS-10. This little bastard works great 
excapt for casual pitch drifts. Sometimes it doesn't play the exact 
pitch when hitting a key, than hitting it once more will make the 
accurate pitch sound. This will also happen when using some "gilde", 
than when gliding to a note sometimes it won't target to the exact 
pitch...

Should I change all electrolytics ? how about ICs ? Which section 
shuold I look at ? VCA ? VCO ?

Thanks